Inductive metering devices are known, for instance, disclosed in the book "Der Hydrauliktrainer, Volume 2, Proportional- und Servoventiltechnik" of Mannesmann Rexroth GmbH, Lohr am Main on page D7. A distance detecting device of the type shown in this book is disclosed in FIG. 1 below. Another known design of a distance detecting device is further shown in FIG. 2 below.
Said known distance detecting devices require a substantial number of components with the consequence, that the space requirement on an electronic card are undesireably large. Moreover, said known distance detecting devices require a relatively large amount of power with the inherent disadvantages. Finally, the sinus voltage at into the distance detecting device has a large distortion factor and therefore a correspondingly large distortion factor when occur at the output of the evaluation circuit (a demodulator) which is arranged following the detecting device.